Hey there!!
Perimeter of a rectangle =2 ( length + width )
Let's take the measure of the width as ' x '
Then, the length would be ' 3x '
Hence,
... 2 ( x + 3x ) = 96
... 2 ( 4x ) = 96
... 8x = 96
... x = 96 / 8
... x = 12
Width = 12 inches
And, length would be 36 inches.
Hope my answer helps!!